After drought (D1-D4) in the contiguous U.S. rose to 21.2% in late October (from a minimum of 2.3% on April 23) when late summer and early autumn flash drought conditions overspread the Southeast and mid-Atlantic, wet weather across the eastern half of the Nation during the past 90-days have nearly eliminated drought east of the Mississippi River.
As of Jan. 7, drought declined to just 11.2% of the lower 48 States, confined to the southern Plains, Four Corners region, and Pacific Northwest. With the expected continuation of storms traversing most of the contiguous U.S. (except in California and the Southwest), improvement of drought is likely in the southern Plains and extreme northern sections of the Pacific Northwest. Likewise in Hawaii, with recent heavy rains and favorable odds for above-normal February and FMA rainfall during the wet season, drought should improve.
In contrast, persistent high pressure over the North Pacific Ocean is expected to continue, diverting storm systems to the north and south and away from California and parts of the Southwest. As a result, development of drought by the end of April is possible in southern Oregon and northern California. In the Four Corners Region, with no clear tilt of precipitation (EC) out through April, persistence was the best bet.
Similarly in Alaska, the small D1 area in the southeastern Panhandle is long-term drought, and with no clear precipitation signal and a declining rainfall climatology, persistence was the forecast there. In Puerto Rico, unfortunately hit by a strong earthquake, recent rains have eliminated the last small D1 area in the southeast.
Forecast confidence is moderate to high for the Southeast Region.
- With surplus precipitation falling on most areas of the Southeast during the past 30 to 90-days (surpluses between 4-12 inches since mid-October), the widespread flash drought that peaked in October across the region has basically disappeared.
- All that remained was a small D1 area in the Florida Panhandle, and some small D0 in eastern parts of Virginia and North Carolina, and northern and southern Florida.
- But with favorable forecasts for above-normal precipitation (7-day QPF, 6-10 and 8-14 day ERFs, Week 3-4, and 1-month LLF), the last remaining drought area should disappear soon, and no drought development should occur by April 30.
Forecast confidence is moderate for the South Region (lower for Texas).
- In the Southern Region, a somewhat complicated forecast for Texas as recent rains brought slight improvement to central and eastern sections of the state, but this area had been trending dry with 60-day precipitation percentages of 25-50%.
- The climatology for FMA is on the dry side, especially early on and in western portions. Forecasts for Texas included decent precipitation in the 7-day QPF, ERFs, and Weeks 3-4, with temperatures expected to cool down in the short-term.
- There was no tilt (EC) in the 1- and 3-month precipitation LLFs, although temperatures were favored to be above-normal. With better skill in the short-term that pointed toward wetness/improvement, the SDO followed suite.
- With the expected widespread improvement, no development is foreseen in the rest of the South.
Forecast confidence is moderate to high for the Midwest Region.
- Although the Midwest region was generally wet at most time periods out to 3-years and currently drought-free, there were some small areas with dryness at 60- to 90-days (Iowa, Missouri, Ohio).
- But with the recent wetness at 30-days, this being the cold season (no evaporation or agricultural impacts), above to much-above normal USGS stream flows, a wet QPF and 3-month precipitation LLF (although cold and dry ERFs, Week 3-4, and 1-month LLF), no development is expected by the end of April.
- In fact, this region could use some drier and warmer weather come spring crop preparation and planting time.
Forecast confidence is moderate for the central High Plains, and high for the northern High Plains Region.
- Similar to the Midwest, the northern High Plains has observed surplus precipitation out to 2 years, and with mostly wet forecast odds from the ERFs to FMA precipitation LLF, no development is expected here by the end of April.
- Farther south, however, the central Plains has been drier in the medium-range (90- to 120-days) in western Nebraska and most of Kansas, but recent rains in the past 60-days eased dryness there.
- Climatologically, February and March are typically dry, with April normals gradually increasingin response to the MJJ wet season. The QPF is fairly dry, but the odds favor above-normal precipitation in the ERFs, Weeks 3-4, and FMA 2020 LLF (Feb 2020 LLF = EC).
- The drought in southeast Colorado and southwest Kansas are close to the areas forecasted for above-normal precipitation, but the farther west one goes, the drought (Four Corners region) is more long-term.
- With no clear forecast for precipitation past the ERFs (all EC), persistence was made here.
Forecast confidence is low to moderate in the Northwest, and moderate in the Southwest (West Region).
- With a large area of high pressure (and above-normal sea surface temperatures) over the North Pacific Ocean, storms have been forced to move either north or south of the ridge, which has resulted in fewer Pacific storms for the central West Coast this Water Year (WY; since Oct. 1), resulting in subnormal WYTD basin average precipitation (60-75%) and snow water content (70-90%).
- The models keep this pattern for a while, and it was reflected in the 8-14 day ERF, Weeks 3-4, and Feb and FMA precipitation LLFs as they all favored subnormal precipitation chances. In the next week, however, stormy weather is expected for the Northwest as a strong storm system impacts the West Coast.
- Overall, enough moisture should reach the extreme northern Pacific Northwest (Washington, Idaho, and Montana) and possibly southern California, but miss the central West Coast (northern California and Oregon).
- Therefore, development (at least D1) by the end of April is forecast for most of Oregon, northern California, and southwestern Idaho. Development was not drawn for southern sections of California and Arizona since this area has been wet during the past 6-months.
- In the Four Corners region, there wasn’t a strong tilt toward any precipitation (EC), and since this is more long-term, persistence was left as the best option.
- Surprisingly, although the WYTD basin average precipitation in most of the West is somewhat below normal, colder conditions have led to more snowfall at lower elevations, producing Jan. 13 SWC that was above-normal in many southern, central, and eastern sections of the West.
Forecast confidence is moderate to high for the Northeast Region.
- The Northeast Region continued to remain drought-free, although a small D0 area persisted on the Delmarva Peninsula.
- With 60- to 90-day precipitation anomalies near normal or wet (but 30-days somewhat dry), USGS stream flows normal or above-normal, 30-day temperatures above-normal but still low (as was evaporation) since it is winter, no drought impacts, and short-term (QPF) wet (but ERFs & Week 3-4 dry, 1- and 3-month precipitation LLFs EC), no drought development is expected through April.
Forecast confidence is moderate for Alaska.
- In Alaska, drought has lingered in the southeastern Panhandle since March 2018. Long-term drought impacts such as low reservoirs for hydro power will continue in parts of the Alaska Panhandle until enough snow pack accumulates for gradual snow melt into the reservoirs, or ample precipitation fills the lakes.
- With the southeastern Panhandle gradually headed out of its typical wet season (fall) and into its dry season (late spring-early summer), and no guidance from the precipitation forecasts (EC), long-term drought was left to persist for the FMA drought outlook.
Forecast confidence is moderate to high for Hawaii.
- In Hawaii, widespread moderate to heavy rains and improvements have occurred recently, and the forecasts favor wet weather at both 1- and 3-month precipitation LLFs as the state heads into the wet season. Therefore, drought is expected to ease or be removed by the end of April.
Forecast confidence is low to moderate for Puerto Rico.
- In Puerto Rico, recent rains have erased drought conditions (D1) in southeastern sections. With the FMA climatology typically dry and the CariCOF JFM 2020 precipitation forecasts of EC for the island, there was not enough information to confidently forecast conditions, although they should not deviate too much through April. Some small areas of drought (D1) may re-develop during FMA, but the official forecast is for no development.